Gable top cartons have been known for the better part of the twentieth century. Their characteristic simplicity and resealability have helped to sustain their popularity as containers for traditional liquid food products such as milk and juice, but in recent years they have been used for products ranging from ammunition to Epsom salts.
Gable-top containers are manufactured from container blanks that are comprised of a flexible laminate which includes a carrier layer of paper between external liquid-tight plastic layers. Stacks of such blanks are supplied to the packaging machine, usually at an input magazine. The blanks have previously been folded and side-sealed so that they obtain a substantially square cross-section when erected within the packaging machine. These blanks are fed individually to the input of the packaging machine where the blanks are formed, filled, and sealed to produce a gable-top container that is filled with product.
The blanks from which the gable-top containers are manufactured are in the form of material sheets which have been detached from a continuous web of packaging material and have been given an outer contour which is adapted to provide the required size and shape of the finished container. For a gable-top container, the blanks have a substantially four-sided configuration in which two parallel lateral edges are straight and define the sides of the blank while a further pair of parallel transverse edges are irregular and define the top and bottom of the blank. The non-uniform edges make it difficult, if not impossible, to establish a rational cutting of the blades edge-in-edge with each other. As such, there is an appreciable amount of waste material associated with the cutting of the blanks from the continuous web of material. This not only brings about increased material costs, but also renders the manufacturing of the blanks difficult since the excess material that is continuously generated during the production process must be removed in a manner which does not interfere with the production process.
One reference addressing the problem of wasted material is U.S. Pat. No. 4,655,386, to Billberg. The '386 patent is directed to a packaging container, such as a gable-top container, which is provided with partly straight, parallel lateral edges, and partly transverse edges which are indented according to a regular pattern which is repeated over the width of the blank. As a result of the indentations, the edges of the blanks can be cut and formed without substantial waste.
When fully folded, filled, and sealed, the known blanks, such as the type disclosed in the '386 patent, form a gable top carton that includes a gabled top structure, including an upstanding fin. The gable top structure engages a plurality of side panels. Traditionally, each side panel is generally perpendicular to each adjacent side panel. The panels are each divided from one another by a single vertical score line extending the entire height of the sidewall. These side panels form the characteristic hollow rectangular body of the container and define the volume of product that a carton can hold.
Such gable-top containers containing product are frequently transported in standard-sized crates. Low volume gable-top containers are thus often transported in the same size crates as used to transport the high volume gable-top containers. In the case of the low volume gable-top containers, however, the containers are stacked within the generally standard-sized crates whereby the upstanding fin of a lower gable-top container engages the bottom of the gable-top container immediately above it.
The present inventor has disclosed a gable-top container having an upstanding fin and a corresponding interlocking container blank. The gable-top container can be readily stacked and can be formed from an interlocking container blank that substantially reduces the amount of material wasted in the blank manufacturing process.